Device for separating a substrate from a carrier substrate

ABSTRACT

Device for separating a substrate from a carrier substrate which is connected to the substrate by an interconnect layer. The device includes a carrier substrate holder with a holding surface for holding the carrier substrate. A substrate holder is located opposite the carrier substrate holder. The substrate holder has a substrate holding surface which can be located parallel to the holding surface of the carrier substrate holder. A separating means is provided for parallel displacement of the substrate relative to the carrier substrate in the interconnected state of the substrate and carrier substrate.

RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.13/265,035, filed Oct. 18, 2011, which is a U.S. National StageApplication of International Application No. PCT/EP10/02054, filed Mar.31, 2010, which claims priority from German Patent Application No. 102009 018 156.3, filed Apr. 21, 2009, said patent applications herebyfully incorporated herein by reference.

FIELD OF INVENTION

The invention relates to a device for separating a substrate from acarrier substrate which is connected to the substrate by an interconnectlayer.

BACKGROUND OF INVENTION

Substrates in the semiconductor industry are wafer-shaped round orrectangular bodies, which are often thinned, fragile, for examplearched, or subject to pretensioning, with a very small thickness ofgenerally less than 300 μm.

Depending on the carrier materials used and the interconnect layer usedbetween the carrier and the wafer, different processes for dissolving ordestroying the interconnect layer are known, such as for example the useof UV-light, laser beams, temperature action or solvents.

Separation increasingly constitutes one of the most critical processsteps since the substrates with substrate thicknesses of a few μm easybreak during stripping/peeling or are damaged by the forces which arenecessary for the stripping process.

Moreover thin substrates have hardly any stability of shape or none atall and typically curl without support material. During handling of there-thinned wafer therefore fixing and support of the wafer areessentially indispensable.

In existing methods and devices the separation of the substrate from thecarrier substrate takes place either by lifting off or by rolling off,with the disadvantage that generally considerable forces are acting onthe sensitive substrate.

SUMMARY OF INVENTION

Therefore the object of this invention is to devise a device fordetaching a substrate as easily as possible from a carrier in anondestructive manner.

This object is achieved with the features of the independent claim(s).Advantageous developments of the invention are given in the dependentclaims. The framework of the invention also encompasses all combinationsof at least two of the features given in the specification, the claims,and/or the figures. In the specified value ranges, values which liewithin the indicated limits will also be disclosed as boundary valuesand they are to be claimed in any combination.

The invention is based on the idea of devising a device and a method forseparating a substrate from a carrier substrate which is connected tothe substrate by an interconnect layer, and in which separation of thesubstrate takes place by parallel displacement of the substrate andcarrier substrate against one another. It is advantageous here if duringthe predominant separation process forces act more or less exclusivelyparallel to a substrate holding surface of the substrate holder whichaccommodates the substrate. Furthermore it is advantageous if thecarrier substrate is separated from the substrate while the carriersubstrate is being spaced apart from the carrier substrate holder foraccommodating the carrier substrate or is being lifted off the holder.In this case, in the transverse direction, for parallel displacement ofthe carrier substrate to the substrate ideally only the force of gravityis acting on the carrier substrate. In particular compressive forcesfrom the carrier substrate do not act in the direction of the substrate.

The configuration as claimed in the invention essentially precludescanting of the substrate with the carrier substrate, especially whenseparation takes place by the action of a force on the periphery of thecarrier substrate.

In one advantageous configuration of the device as claimed in theinvention, it is provided that there are means for reducing theconnecting force caused by the interconnect layer. The interconnectlayer can be a cement which can be provided as a thermoplastic or wax ina thickness from 0.01 μm to 500 μm between the substrate and the carriersubstrate. The cement is at least partially liquefied by heating or UVirradiation or another known method in order to minimize the adhesiveforce which is counteracting the separation of the substrate and carriersubstrate by the cement. The reduction of the connecting force takesplace advantageously before separation of the substrate from the carriersubstrate.

In another advantageous configuration of the invention, the separatingmeans comprise a guide carriage which can be driven especially by alinear drive for parallel displacement of the substrate relative to thecarrier substrate. The parallel displacement as relative motion can takeplace by movement of the substrate with the carrier substrate fixed orby movement of the carrier substrate with the substrate fixed or bymovement of the carrier substrate and the substrate. A configuration isespecially advantageous in which the substrate remains fixed on thesubstrate holding surface of the substrate holder and is displacedparallel relative to the laterally fixed carrier substrate. In this waythe substrate can be protected against breaking specifically during theseparation process by the substrate holding surface.

In another advantageous configuration of the invention it is providedthat the separation means comprise raising means for raising thesubstrate which is connected to the carrier substrate, especially byraising the guide carriage. By raising the substrate-carrier substratecombination which consists of the carrier substrate, the interconnectlayer and the substrate, separation of the substrate from the carriersubstrate can take place when the carrier substrate is floating so thataside from the force of gravity acting on the carrier substrate itself,no other forces acting transversely to parallel displacement are actingon the carrier substrate.

By the carrier substrate holder comprising carrier substrate fixingmeans for fixing the carrier substrate on the holding surface and/or thesubstrate holder comprising substrate fixing means for fixing thesubstrate on the substrate holding surface, both the substrate and alsothe carrier substrate can be fixed most easily directly to the carriersubstrate holder or substrate holder. Advantageously, fixing takes placeby applying a negative pressure or vacuum to part of the contact surfaceof the substrate or carrier substrate with the substrate holder or thecarrier substrate holder.

To the extent the separating means comprise, especially exclusively,holding means which act against parallel displacement, especially stopsattached to the carrier substrate holder or the substrate holder, aforce which counteracts the parallel displacement for separating thesubstrate from the carrier substrate can be applied extremely easily tothe carrier substrate or the substrate. The force acts in this waysolely on the side or the periphery of the substrate or carriersubstrate so that transverse forces are not produced by the holdingmeans.

According to one special aspect of the invention it is provided that thelinear drive is assigned a drive control with which the speed ofparallel displacement can be controlled by the guide carriage 8. It isespecially advantageous here to measure the stripping force for controlof the speed with dynamometric means since the stripping force isdependent among others on the contact area between the substrate andcarrier substrate which changes during the stripping process. To measurethe force, dynamometer cells can be used as the dynamometric means orthe power consumption of the linear drive can be measured. A velocitywhich increases according to certain stipulations from the start ofstripping to the end of the stripping process, without the influence ofdynamometric means, is less complex.

Advantageously stripping takes place at a constant stripping force. Thespeed of parallel displacement is accordingly indirectly proportional tothe active contact area between the substrate and the carrier substrate.

The method as claimed in the invention for separating the substrate froma carrier substrate which is connected to the substrate by aninterconnect layer in its most general form has the following steps.

-   -   Holding a substrate-carrier substrate combination which consists        of the carrier substrate, the interconnect layer and the        substrate between the substrate holding surface of a substrate        holder and the holding surface of a carrier substrate holder,        which latter surface can be located parallel to the substrate        holding surface,    -   Separating the substrate from the carrier substrate by parallel        displacement of the substrate relative to the carrier substrate        in the interconnected state of the substrate and the carrier        substrate.

In one advantageous configuration of the invention, a connecting forcewhich is caused by the interconnect layer is reduced after holding andbefore separation. In this way the force necessary for separationbecomes smaller and damage to the substrate or carrier substrate isprevented.

In one advantageous embodiment of the method as claimed in the inventionseparation takes place by a guide carriage which can be drivenespecially by a linear drive for parallel displacement of the substraterelative to the carrier substrate. Especially exact paralleldisplacement can be implemented on the guide carriage.

According to another advantageous configuration of the invention, it isprovided that before separation the substrate-carrier substratecombination is raised after the fixing of the carrier substrate on thecarrier substrate holder has been optionally cancelled. The carriersubstrate can then be separated from the substrate in a freely floatingmanner.

In another advantageous embodiment of the invention, it is provided thatthe separation of the substrate from the carrier substrate takes placeat least predominantly solely by parallel displacement. At the start ofthe separation process which proceeds by parallel displacement thecontact area between the substrate and the carrier substrate is largest,so that at the start of the separation process the separation forcewhich is necessary for separation is greatest and it continuouslydecreases up to complete separation of the substrate from the carriersubstrate. In this respect, after at least predominant separation of thesubstrate from the carrier substrate an additional force component canalso be applied transversely to parallel displacement.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages, features and details of the invention will becomeapparent from the following description of preferred embodiments andusing the drawings.

FIG. 1 shows a schematic side view of the device as claimed in theinvention in a first process step,

FIG. 2 shows a schematic side view of the device as claimed in theinvention in a second process step,

FIG. 3 shows a schematic side view of the device as claimed in theinvention in a third process step and

FIG. 4 shows a schematic side view of the device as claimed in theinvention in a fourth process step.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

In the figures the same components and components with the same functionare identified with the same reference numbers.

The device shown in FIGS. 1 to 4 consists of a stable base plate 9 whichvibrates as little as possible. Above the base plate 9 there are theother components of the device which are mechanically connectedespecially to the base plate 9; this is not shown in the schematic.

A carrier substrate holder 5 rests on the base plate 9; it is made as achuck and with its side facing away from the base plate 9 it is used asa holding surface 5 a for holding the carrier substrate 2.

The carrier substrate 2 can be fixed by carrier substrate fixing means 7which are formed in the embodiment as vacuum grooves on the holdingsurface 5 a and thus on the carrier substrate holder 5.

Fixing can be controlled by the corresponding control means.

Laterally next to the holding surface 5 a which is intended foraccommodating the carrier substrate 2, on the carrier substrate holder 5there are holding means 10 which can be made pluggable. Thus,replacement of the holding means 10 for carrier substrates 2 ofdifferent thickness is possible and the holding means can be adapted tothe size of the carrier substrate 2. By providing several plug positionson the periphery of the carrier substrate 2 different forms and sizes ofthe carrier substrate can be implemented.

Opposite the base plate 9 or the carrier holder 5 a guide carriage 8with a linear drive which is not shown is located parallel to theholding surface 5 a. On the guide carriage 8 a substrate holder 4 with asubstrate holding surface 4 a for accommodating a substrate 1 is mountedto be able to move parallel to the holding surface 5 a.

The substrate 1 can be fixed by substrate fixing means 6, here vacuumgrooves, in the conventional manner on the substrate holder 4 in theregion of the substrate holding surface 4 a.

Fixing by the substrate fixing means 6 or the carrier substrate fixingmeans 7 can alternatively take place by electrostatic fixing or bymechanical clamping.

The guide carriage 8 and thus the substrate holder 4 can be movedorthogonally to the holding surface 5 a or to the substrate holdingsurface 4 a by a Z-guide carriage 12 which is located orthogonally tothe guide carriage 8 with a linear drive. The Z-guide carriage 12 isused as a raising means for raising the substrate 1 which is connectedto the carrier substrate 2.

The substrate 1 is connected to the carrier substrate 2 by aninterconnect layer 3, for example a thermoplastic cement. Thearrangement of the substrate 1 and of the carrier substrate 2 and thusthe substrate holder 4 and the carrier substrate holder 5 can also bereversed, i.e. turned by 180°.

In the process step shown in FIG. 1, the holding of thesubstrate-carrier substrate combination which consists of the substrate1, the interconnect layer 3 and the carrier substrate 2 by the substrateholder 4 and the carrier substrate holder 5 is shown. Perfectly parallelalignment of the substrate holder 4 or of the substrate holding surface4 a relative to the carrier substrate holder 5 or the holding surface 5a is of special importance.

Then the substrate-carrier substrate combination as shown in FIG. 2 isslightly raised by the guide carriage 12, exactly orthogonally to theholding surface 5 a, so that in the subsequent parallel displacement asshown in FIGS. 3 and 4 there is no contact between the holding surface 5a and the carrier substrate 2. The carrier substrate 2 is advantageouslyraised by a raising height A of less than the height T of the carriersubstrate.

Following the raising as shown in FIG. 2 or during the raising as shownin FIG. 2, the connecting force which is caused by the interconnectlayer 3 between the substrate 1 and the carrier substrate 2 is reducedby means for reducing the connecting force, for example by temperatureaction.

In the process step as shown in FIG. 3, parallel displacement of thesubstrate 1 along the guide carriage 8 which is caused by a linear motor(not shown) takes place. Until the carrier substrate 2 strikes theholding means 10 which are made as pins, there is still no relativemotion between the substrate 1 and the carrier substrate 2. As soon asthe carrier substrate 2 strikes the pin or pins, the substrate 1 beginsto be separated from the carrier substrate 2 by parallel displacement ofthe substrate 1 relative to the carrier substrate 2. Aside from theforce of gravity acting on the carrier substrate 2 by the weight of thecarrier substrate 2, during parallel displacement transverse forces arenot acting so that damage of the sensitive substrate 1 which is moreoverprotected by the substrate holder 4 is more or less precluded.

In FIG. 4 the separation process is completed, the separation processnot having to consist solely, but only predominantly, of paralleldisplacement, since the adhesive force caused by the interconnect layer3 between the substrate 1 and the carrier substrate 3 during theseparation process continuously decreased and towards the end of theseparation process displacement in the orthogonal direction can takeplace in addition to the parallel displacement. To the extent thecarrier substrate 2 however is to be deposited in the position as shownin FIG. 4 after the separation process, it is advantageous to effect theseparation process completely by parallel displacement. Alternatively,the carrier substrate 2 can be peeled off the substrate towards the endof the separating process by the fixing means 7 which are made as vacuumgrooves.

DESCRIPTION OF REFERENCE NUMERALS

-   1 substrate-   2 carrier substrate-   3 interconnect layer-   4 substrate holder-   4 a substrate holding surface-   5 carrier substrate holder-   5 a holding surface-   6 substrate fixing means-   7 carrier substrate fixing means-   8 guide carriage-   9 base plate-   10 holding means-   12 Z-guide carriage

Having described the invention, the following is claimed:
 1. Device forseparating a substrate from a carrier substrate wherein the carriersubstrate is connected to the substrate by an interconnect layer, thedevice comprising: a carrier substrate holder with a holding surface forholding the carrier substrate, a substrate holder which is locatedopposite the carrier substrate holder, the substrate holder having asubstrate holding surface wherein the holding surface of the carriersubstrate holder is capable of being located parallel to the substrateholding surface of the substrate holder, a guide carriage connected tothe substrate holder, the guide carriage movable in a direction parallelto a surface of the carrier substrate when the carrier substrate isinterconnected to the substrate, a drive control unit controllingmovement of the guide carriage, the drive control unit programmed tovary a speed at which the guide carriage moves the substrate relative tothe carrier substrate based on the shear force required to separate thesubstrate from the carrier substrate, and at least one dynamometer cellfor measuring the shear force between the substrate and the carriersubstrate.
 2. Device as claimed in claim 1, further comprising means forreducing the connecting force caused by the interconnect layer. 3.Device as claimed in claim 1, wherein the guide carriage includes alinear drive for parallel displacement of the substrate relative to thecarrier substrate.
 4. Device as claimed in claim 3, wherein the lineardrive is connected to the drive control unit for adjusting the speed ofparallel displacement of the guide carriage.
 5. Device as claimed inclaim 3, wherein the drive control unit determines the shear force basedon the power consumption of the linear drive.
 6. Device as claimed inclaim 1, wherein the carrier substrate holder comprises carriersubstrate fixing means for fixing the carrier substrate on the holdingsurface of the carrier substrate holder.
 7. Device as claimed in claim1, wherein the substrate holder comprises substrate fixing means forfixing the substrate on the substrate holding surface of the substrateholder.
 8. Device as claimed in claim 1, further comprising stopsattached to the carrier substrate holder or the substrate holder, thestops having a surface dimensioned to engage the carrier substrate orthe substrate to hinder parallel displacement of the substrate relativeto the carrier substrate.